Adventures with a Soldering Iron Part 2 (DAC Build)

Having enjoyed building (well, assembling) my nCore amps I've decided to have a crack at building a DAC. This build will be a bit more complicated because the DAC will arrive as a pile of bits that need soldering onto the respective boards.

So which DAC is it I hear you say? Here is a link to the designer's website that explains all about it:

It's a NOS DAC based on the PCM1794 chip. My initial build will consist of one DAC board but it is possible to stack the boards. In standard form the only input is USB, but it is possible buy an S/PDIF board for it as well. Output transformers or fancy caps can also be added but for now I'll stick with the basic build, consisting of:

DAC board

USB input board

5v power supply for USB

12v power supply for DAC board

Total cost for these parts was £350.

I've heard a version of this DAC with four boards/upgraded caps which was very impressive. Just need to find a suitable case for it now and I can start building. Pics and more information to follow soon.

Has the DIY bug bitten? - I mean, do you simply fancy making your own gear - or do you expect to make something that is better than the Perfectwave, the Octave, Weiss, etc?

I take it the modded DIY DAC you heard must have been pretty special?

The DAC I heard had four DAC boards plus mundorf caps. It's about three times more expensive in this guise. Sound quality was very good - didn't have my DAC with me to compare, so Im hoping the DIY DAC runs it close for SQ, although the features count will be well down on my current DAC.

Definitely looking forward to the build and hoping to learn a lot more about electrical circuits than I do now.

Top two boards are for the power supplies. One 5v for the USB board and a 12v for the main board. The bottom board is the main board with the DAC board in position:

Shot below shows how much case space will be required to accommodate the supplies, main board and USB board. The power supplies can be stacked using spacers but I would prefer to have a wide slim case.

Plenty of soldering to do......

Close up of the DAC board. Everything is very clearly labelled so this doesn't look like it will be a complicated build. The boards look to be very high quality:

One of the transformers with heat sinks:

Very much looking forward to getting going with this build. I was concerned it might be beyond my basic DIY skills but having received the kit and looked through it I think I should be ok.

Hey James, I'm very drawn to following you down this rabbit hole with my soldering iron and seeing what lies at the end of the tunnel...

My soldering isn't that great and I worry about making a mess of it, so I'll wait for you to do it first

BTW, did you go for any of his upgrade options?

And do you plan to eventually go for the 4 DAC board option?

Hi Jason, no plans to go for 4 DAC boards or the Sowter transformers at this stage. There are posts on DIY Audio indicating that there is more benefit to be had from using Tentlabs shunt regulators on a single DAC board, compared to buying four boards. The regulators are about £35 each I think and four are required. This is quite a bit cheaper than buying three more boards.....note that the 12v supply can support 8 boards which some people are now using. Costs soon mount up if you buy 8 boards, plus shunt regs for every one.

The output transformers are meant to improve the sound but I don't want to end up with no play on my pre's volume control as a side effect. They are also something line £650 per pair.

I might look at upgrading some of the resistors over time. Audio Note tantalum resistors are meant to offer an improvement over the supplied resistors, but I would need eight of them at £15 each :-O

With regard to the soldering - if I can do it anyone can. The only thing I've soldered before is the XLR and IEC connectors on my amps - in doing this I only melted two IEC inlet sockets

James, that's really useful info on the upgrades and sounds like I should read up on diyaudio first and plan exactly what flavour of this I want to build before committing any cash.

I'm still going to wait for you to do it first though. And then I'll orchestrate a dac-off at your place and make you think it was all your idea and I'll invite myself round and eat all your muffins...

No case sorted yet. Will build it on a piece of board first. The shunt regs replace surface mount items (four of them) so It's better to have them before starting the build to avoid desoldering. I've not ordered mine yet as waiting on feedback as to whether they are a worthwhile improvement.

aaargh. dd is away on business at the moment apparently so i have no idea when i will get the kit. i am off work next week so had some time to make a start on it.

Great project James. The only tip I can offer RE soldering is to steer well clear of lead free solder, especially if this is a first kit attempt. It's difficult to use properly and on a kit that involved, if soldering skills aren't well practised, you'll likely end up with a lot of "cold" solder joints. Leaded solder is much more forgiving, flows better, is less prone to cold jointing and easier to use (lower melting point).

Also, RE AN Tantilium resistors...lets just say that my strong belief is that sticking with the resistors you have and weeding out any that are over 0.5% out of spec would be a wiser choice. The biggest difference using the AN ones will have I suspect will tend to be in your wallet and nothing else. Avoid this penchant for foo resistors as its the rating, type of resistor and tolerance that matter, not what designer label they use. Do you remember the Deuland foo resistor debacle a short while back? Someone paid silly money for them, and broke one accidentally. What do you think he found inside the ceramic casing? It was a pencil lead LoL (seriously).

I'll watch this with interest as it's a kit I was considering myself. Have your sorted wiring? I'd be tempted to use (properly rated) solid core OFC hook-up wiring and use shielded wiring for the signal incomers and outgoing wiring.

Solder'll be fine. Avoid using silver plated copper or silver cable as that needs silver solder or one of the many quad eutectic solders using silver/lead/copper/tin (best ones but pricey). RS components is another good source for wiring etc.

Both power supplies and DAC board assembled over weekend. Just waiting on delivery of wire to run from output points on main board to the RCA outputs. Both power supplies turn on fine but I've yet to measure the outputs with a multimeter. That'll be a job for next weekend before doing the last bit of soldering.

The MDF board shown in the photo is the same footprint as my PS Audio DAC. I think the final case might end up being taller than my existing DAC due to the height of the heatsinks on the power supply boards.

Top right-hand circuit board is the USB input. This can be powered by the USB input cable or via the 5v power supply board (which seems a no brainer).